Research on genetic diversity of Chinese population of the crested ibis.

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The objective of this study is to measure the level of genetic diversity of a population of the crested ibis, an endangered species, in China, and to establish genetic markers that can be utilized for monitoring inbreeding status of individual animals. For this purpose, we collected DNA sapmles from dead animals and examine genetic variations among the samples. First, we determined a partial nucleotide sequence of mitochondrial DNA (mtDNA), and analyzed phylogenetic relationship between the crested ibis and its related species, Our data shows that the crested ibis is most closely related to Plegadis falcinellus, Glossy Ibis. We, however, found no variation in mtDNA sequence among individuals. On the other hand, variations at individual level were found by the method of amplified fragment length polymorphism (AFLP). In AFLP experiment, we used EcoRI and MseI restriction endonucleases to generate DNA fragments. Then we used EcoRI-restricted primer and MseI-restricted primer to amplify selected DNA fragments At final step of AFLP, we used 12sets of selective primers to limit the number of DNA bands in the analysis. Two sets of the primers gave different fragment pattern for individual samples, The result suggest that AFLP would be applicable to determine pedigree structures in the crested ibis population if more AFLIP markers are identified. Other nuclear markers such as microsatellite and non-coding sequences were also identified in the sample population, however, no variation was found among samples so far. We also sequenced a part of major histocompatibility complex loci, but failed to find genetic variations. Those data suggest that the population of the Chinese crested ibis is tinder extreme inbreeding condition and the level of genetic diversity is greatly reduced, although some variations still exist.